Preliminary evidence presented in this proposal suggests that the sexually infantile state in the female rhesus monkey is accompanied by, and perhaps maintained by, an enhanced metabolic clearance rate for estradiol. This finding, together with a presumed low (but as yet unmeasured) ovarian estradiol production rate, and the probability of high circulating levels of sex hormone binding globulin (SHBG), suggest that a physiological conspiracy may exist during sexual immaturity to restrict the access of estradiol to target tissues and hence hinder secondary sexual development. I propose to measure, and determine the role of: (1) changes in the metabolic clearance rate for estradiol (using the technique of constant infusion of tritiated estradiol), (2) changes in circulating estradiol levels (by radioimmunoassay) and circulating sex hormone binding globulin (SHBG) and unbound estradiol (using differential dissociation techniques), and (3) changes in ovarian production rate of estradiol during puberty in the female rhesus monkey.